I’ve seen many posts about this and as most of us know its a very easy mod. But I figured that it couldn’t hurt to do it since we’re getting more and more members everyday. Someone can benefit I’m sure.
Noobs: its a great mod and I tried to be as detailed as I could be from memory. Hope it helps and have fun!
Everyone else: feel free to add your comments, tips, tricks, etc. here. Especially if I missed anything. 
Installing 1-piece Headlights
Have the following items with you before you begin:
[list=1]
10mm and 12mm sockets (pretty sure on size)
Philips screwdriver
A socket wrench
A long extension
Wire cutters/wire strippers
Electrical tape
A soft blanket or towel
A small container to put the screws and bolts in
6 wire nuts for 18-24 gauge wire or your electrical connector of choice
Electrical tape
A print out of the Helms manual instructions for reference is helpful
[/list=1]
Prep work
- Find a nice, dry, well-lit place to work in
- Lay the blanket or towel on the ground close by. It should be big enough to hold your front bumper and headlight housings.
- Your new JDM 1-piece headlights w/harnesses and extension wires already attached (this guide assumes you have the extensions already made. Basically its extra wire soldered on to the harness to give you some slack when connecting. Search if you don’t get it
)
Bumper Removal
- Use the Phillips screwdriver to remove the bumper turn-signals by unscrewing the screw (1 on each housing) and pull out. Save the screws in the container. Unplug the wire harnesses from the back of each assembly and set the housing to the side.
- Unbolt the four bolts (2 behind each bumper light housing) and place them in the container. You will need to use the wrench and extension to reach. 12mm socket for these, I think.
- Unscrew the 4 bumper mounting screws (2 on either side of the bumper, in the wheel well) and place them in the container.
- Unscrew the 2 clips from the bumper. They are on the underside of the bumper, behind the lip, on either side of dead center. They unscrew and then you have to pry out the small casing that they reside in.
- Lift and remove the bumper by sliding it forward. Its not heavy, but a friend would be helpful, just so you don’t scratch it. Lay it on the blanket.[list=a]a. At this point you can also remove the intake resonator, if you haven’t already done so. Search G2ic for the location of the 3 bolts holding it in.[/list=a]
Headlights - Removal - Unplug the wiring harness on the back of the housings. There are 3: 2 for the corner lights and 1 for the headlights and fog-lights. Mark the one that is used for the “driving” lights (front one, I think) for easier identification later.
- Unbolt the 5 screws holding in the headlight housings. (5 per housing, 10 total) 10mm for these.[list=a]a. 3 are on the top of the housing. The other 2 are below.
b. Remember to save them and put them in the container.[/list=a]8. Carefully lay the housings on the ground.
Headlights – Wiring
9. Take the wire cutters or razor blade and cut the plug off of the harness from the headlight/fog-light only! Make the cut so you leave yourself enough room to splice the remaining wire, but also enough to add wire to the old plug for the member you sell yours to 
10. Use the wire strippers to strip off about ½ inch from the wires that you cut the plug off of.
11. Remove the headlight plug from the 1-piece headlights that you bought.
12. Match up the colors of the wire on both ends (the new plug and the wires to the harness in your car). Use your connectors (wire nuts, butt connectors, etc.) to secure the wire to each other. [i]I would recommend you also tape the connections using the electrical tape, but do it later, once you test and make sure everything works[/i]
Headlights – Installation
[i]If you intend to do the H4H-to-H4 conversion, do it before continuing. See G2ic for more info on this mod[/i]
13. Take 1 of the new 1-piece housings and line it up to the holes in the frame (3 on top, 2 on bottom. Use the bolts from the container (same ones you took off) to gently hold the housing in place. DO NOT OVERTIGHTEN! Just to a snug position for now.
14. Plug in the corner lights. Use the plug that you marked earlier. It should be the one that used to turn on your driving lights (when you test them out, the corners should turn on with your driving lights, the setting before the headlights come on). The other one can hang, but you should remove the bulb.
15. Plug in the headlights. Remember to lock down the retaining ring nut to hold the bulb in place.
16. Do the same for the other side.
Headlights – Testing
17. Make sure all your connections are secure and go turn on the lights. [list=a]a. Check the driving lights first. They should come on when the switch is in the first position.
b. Next check the headlights.
c. Check the turn signals.
d. Finally check the fog-lights.
e. If everything comes on, you’re done!
f. Tape the connections and tighten down the bolts to a snug fit.
g. Aim the headlights (search G2ic for exact location of adjustment screws/methods of doing it)[/list=a]
Final Notes
18. Put the bumper and the bumper lights back the reverse of taking it out. Remember to check the signals making sure they work.
19. Be careful not to scratch the bumper. If it doesn’t fit exactly right, try again. Don’t get mad and try to force it into place.
20. Tighten all screws/bolts to a nice snug fit.
21. If the housings don’t look like they line up properly, you’re bolts are probably too tight. Loosen them.
If you have questions, most answers can be found on G2ic via the SEARCH button.
-newtegguy